The present invention generally relates to identifying to which phase of a polyphase electric power supply system a device is connected.
In many countries, the exact structure of the electric power supply network is not known, especially the parts of the electric power supply network located between substations' transformers and subscribers' premises. In particular, the mains phases are not clearly identified once low-voltage cables exit the substations. It is therefore complex for an installer to determine on which phase an electricity meter is being connected. This causes numerous problems to the operator of the electric power supply network, in particular for low-voltage network supervision and load balancing at transformers.
It is therefore desirable to be able to determine to which mains phase an electricity meter, or an interface of such an electricity meter, is physically connected.
This problem also occurs in the context of polyphase electric power supply systems for devices other than electricity meters, whenever cross-phase communications may take place, since such cross-phase communications frequently require installing additional devices in order to increase reliability of the communications.
The document “IEC 61334-5-1:2001, Automatisation de la distribution à l'aide de systèmes de communication à courants porteurs—Partie 5-1: Profils des couches basses—Profil S-FSK (modulation pour saut de frequencies étalées)” provides a mechanism for determining the phase to which a receiver device is connected. The mechanism relies on a transmission by a transmitter device of PHY frames exactly at an instant at which an alternating electrical signal transmitted on the phase to which the transmitter device is connected performs zero-crossing. The receiver device is then able to determine the phase to which the receiver device is connected by determining the delay between zero-crossings detection by the receiver device and receptions of PHY frames. This mechanism is however not applicable in situations wherein the frame transmissions cannot be forced to occur synchronously with zero-crossings of the alternating electrical signal. Indeed, rendering asynchronous the frame transmission from the shape of the alternating signal allows increasing the communication bandwidth. For instance, this mechanism is not applicable in the context of the PRIME (PoweRline Intelligent Metering Evolution) standard or in the context of the G3-PLC specification, as defined by the ITU document “G.9955 Annex A—G3-PLC PHY Specification for CENELEC A Band”. 
Another solution, proposed in the context of the PRIME standard task force, is for the transmitter device to determine time gaps between zero-crossings of the alternating electrical signal and the transmissions of beacons, which are transmitted at fixed time intervals. Values of the determined time gaps are then transmitted by the transmitter device to the receiver device in the beacons. The receiver device is then able to determine the phase to which the receiver device is connected on the basis of the time gap values provided by the transmitter device and of the delay between zero-crossings detection by the receiver device and receptions of PHY frames. However, this solution generates significant overhead costs.
It is desirable to overcome the aforementioned problems of the prior art. In particular, it is desirable to provide a solution that allows determining the phase to which the receiver device is connected although powerline communications occur asynchronously from the shape of the alternating electrical signal, and furthermore, with limited overhead.
It is furthermore desirable to provide a solution that allows the receiver device determining whether the receiver device is connected in a phase reversal manner.